Hi,
I have a stack of 2d images in a 3d coordinate system, numbered sequentially from 1 to N. For each image I have:
1) The 3d coordinate of its origin pixel (the upper left corner of the image).
2) For each image, a pair of cosine vectors which describe the direction the rows and columns are running in the 3d coordinate system:
http://i87.photobucket.com/albums/k153/bnf_intro/image_object.jpgWith those two pieces of information, I can tell where the image is located and its orientation in the 3d space. They look like a loaf of sliced bread, each slice having a number 1 - N.
http://i87.photobucket.com/albums/k153/bnf_intro/in_3d_space.jpgMy question:
Imagine the images are red on the 'front' and blue on the 'back'. If I am looking at these images in a 2d viewer in succession, I'd only see one color as I flip through them. If I were in the 3d space, I could pass through them from front to back, or back to front, so I would end up seeing red OR blue depending on which side I chose to pass through the images from.
Is there a way that I could tell which direction I'm passing through the images in a 2d viewer (the camera in a 2d viewer always passes through the images in numeric order, regardless of their actual position in 3d space).
So this would be 'backwards':
http://i87.photobucket.com/albums/k153/bnf_intro/backwards.jpgand this would be forwards:
http://i87.photobucket.com/albums/k153/bnf_intro/forwards.jpgThe best way I can describe it in english is that 'forwards' means the viewer is walking forward from image #1 to image #N. Backwards means the viewer is walking in reverse from image #1 to image #N.
Maybe it has something to do with the normals of the images and of the viewer? It is utterly confusing to me and hopefully you understand what I'm talking about here. Thanks for any suggestions.
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